Pivoted stretch bending machine with two concentric selectively operable cylinder motors for tensioning workpiece



Sept. 8, 1959 B F. RAYNES 2 PIVOTED STRETCH BENDING MACHINE WITHTWO CONCENTRIC SELECTIVELY OPERABLE CYLINDER MOTORS 'FOR TENSIONING WORKPIECE 4 Sheets-Sheet 1 Filed May 14, 1956 I il I J It IN VEN TOR.

BF. RAYUES BY ATTO RNRY Sept. 8, 1959 B. F. RAYNES 2,903,039

PIVOTED STRETCH BENDING MACHINE WITH TWO CONCENTRIC SELECTIVELY OPERABLE CYLINDER MOTORS FOR TENSIONING WORKPIECE Filed May 14, 1956 4 Sheets-Sheet 2 IN VEN TOR.

BF. RAYM as ATTOQNEY Sept. 8, 1959 B. F. RAYNES 2,903,

PIVOTED STRETCH BENDING MACHINE WITH TWO CONCENTRIC SELECTIVELY OPERABLE CYLINDER MOTORS FOR TENSIONING WORKPIECE 4 Sheets-Sheet 3 Filed May ,14, 1956 w I, m .5

INVENTOR.

B.F. EAYNES M T O Q NE! Sept. 8, 1959 B. F. RAYNES 2,903,039

PIVOTED STRETCH BENDING MACHINE WITH TWO CONCENTRIC SELECTIVELY' OPERABLE CYLINDER MOTORS FOR TENSIONING WORKPIECE Filed May 14, 1956 4 Sheets-Sheet 4 INVENTOR.

BF. R AYN ES ATTORNEY United States Patent PIVOTED STRETCH BENDING MACHINE WITH TWO CONCENTRIC SELECTIVELY OPERABLE CYLINDER MOTORS FOR TENSIONING WORK- .PIECE Burt F. Raynes, Chula Vista, Calif., assignor to Rohr Aircraft Corporation, Chula Vista, Calif., a corporafion of California Application May 14, 1956, Serial No. 584,676

3 Claims. (Cl. 153-40) This application is a continuation in part of my application Serial No. 341,728, filed March 11, 1953 (subsequently abandoned) and the invention relates to a machine for forming metal parts such as strips, rods, tubes and extruded bars into desired shapes by subjecting them to a stress about equal to, or slightly in excess of, their elastic limits and forcing them against the side face of a curved die while under such stress.

The stress applied to workpieces in this manner varies a great deal depending on their cross-sectional areas and those of large cross-section require large forces. These forces are usually applied to the workpiece by gripping one end of it by the jaws of a chuck associated with the die and the other end by a chuck attached to one end of a piston rod the other end of which carries a piston movable in a hydraulic cylinder. The stretching force applied to the workpiece depends on the size of such piston and cylinder and for workpieces of small crosssectionalarea, a small piston and cylinder is convenient to use yet is capable of generating sufficient stress in the workpiece to secure proper bending. However, for workpieces of large cross-sectional area, the stress required is often beyond the capacity of the small piston and cylinder and it is a main object of my invention to provide a hydraulic assembly which is compact yet includes both large and small pistons and cylinders capable of stretching workpieces having a large range of cross-sectional areas. 7

In applying stress to a workpiece while forming it on a curved die, it is necessary that the tension be applied symmetrically with reference to the center line of the workpiece so that the applied stress is uniformly distributed throughout the workpiece. Accordingly a further object of the invention is to provide a forming machine having a hydraulic cylinder and piston for stressing a workpiece in which means is provided for easily raising and lowering the cylinder to bring its center line into alignment with the center line of the workpiece.

If the face of the die against which the workpiece curved die, the tension must be sufficient to stretch the material to, or somewhat in excess of, its elastic limit to overcome the tendency of the metal ,to resist conformance to the shape of the die by its own elasticity. To avoid any additional stress being applied to the workpiece while it is being formed, it is necessary that the tension be applied in a direction tangent to the face of the forming die.

It is, therefore a further object to provide a forming machine having a hydraulic cylinder so pivotally mounted that the tension is continually applied to the workpiece in a direction tangent to the face of the forming die.

cylinder 31.

Patented Sept. 8, 1959 ICE Other objects Will become apparent as a description of the forming machine proceeds. For a better understanding of the invention reference is made to the accompanying drawing, in which:

Fig. 1 is a side view with portions broken away and portions omitted for clarity of a forming machine embodying the invention;

Fig. 2 is a top view of the machine of Fig. 1 also showing the drive means for rotating the forming die;

Fig. 3 is a view partly in section taken on line 3- -3 of Fig. l;

Fig. 4 is a longitudinal sectional view through the cen ter of the hydraulic cylinders of the machine and a schematic view of the fluid supply system;

Fig. 5 is a top view similar of Fig. 2 showing a larger workpiece in position for forming also showing one en of the hydraulic cylinders in section; and

Fig. 6 is a detail elevational view of a modified die.

The forming machine illustrated comprises a main supporting base 10 at one end of which a rotary die-supporting table 11 is mounted for rotation about a vertical axis 12, the table being rotated in either direction by an electric motor 13 through speed reducing gearing 90 and a worm 91 which drives a worm gear 92 secured to the bottom of table 11. A die 14 made of steel or other rigid material is secured to supports 15 a suitable distance above table 11, the die having a side curved forming face 16 which determines the shape of the portion of workpiece 17 pulled against it. The table also carries a support 18 having a pivot pin 19 on which is pivotally mounted a chuck 20 of known type which contains pneumatically operated jaws which firmly grip the end 21 of workpiece 17. Chuck 20 is of a known type and its jaws may be removed and replaced by others shaped to fit workpieces of different cross-sectional shapes.- Tension of an amount later described is applied to workpiece 17 at its other end 22 which is gripped by a chuck 23, this chuck containing pneumatically operated jaws similar to those in chuck 20. Chuck 23 is internally threaded so that it may be screwed onto the threaded end 24 of a small piston rod 25. The opposite end of this rod (see Figs. 3 and 4) carries a piston 26 slidable in the cylindrical bore 27 of a tubular piston rod 28 one end of which is enlarged to provide a piston 29 slidable within the cylindrical bore 30 of a surrounding hollow cylinder 31. Piston 29 has a central bore 32 to pass pressurized fluid into or out of bore 27 and one end of cylinder 31 has attached thereto a closure cap 33 having a central bore 34 to pass pressurized fluid into or out of The opposite end of cylinder 31 has a closure cap 35 provided with a cylindrical bearing face 36 with which the outer cylindrical face of tube 28 has sliding contact. Closure cap 35 has an opening 37 i to admit pressurized fluid into the end of cylinder 31 and at its end has two threaded holes 38 (Fig. 2) adapted to receive the threaded ends of two bolts 39. These bolts pass through a closure cap 40 attached to one end of tube or piston rod 28, the center of cap 40 having a screw thread 4-1 of substantially larger diameter than that of piston rod 25 to provide clearance space between the thread and rod. One end of tube 28 has an inwardly extending flange 42 whose center is bored to provide a cylindrical bearing face 43 which supports and guides piston rod 25. Flange 42 also has a bore 44 to admit pressurized fluid into one end of tube 28.

Cylinder 31 is mounted on main base 10 by means of a large base plate 45 to which a pair of vertical side plates 46 are attached, the top of these plates being connected by a horizontal support plate 47. Plate 45 is guided along base 10 by means of a projecting tongue 48 on base 10 which fits in a mating groove cut in plate 45 (Fig. 3). This tongue and groove connection prevents plate 45 from shifting laterally on base when lateral pressure is exerted on plate 45 during a forming operation. Plate 45 may be set at various distances from table 11 to accommodate workpieces of various lengths, sets of threaded holes 49 (Fig. 2) being. provided in base 10 to receive bolts 50 which pass through plate 45 and secure it in place. To provide for the vertical adjustment of cylinder 31, a pair of solid steel guide posts 51 have their lower ends seated in plate 45 and their upper ends seated in plate 47, a cage 52 which supports cylinder 31 being guided by these posts. Cage 52 comprises upper and lower plates 53, 54 which are connected to the ends of two tubes 55 which have sliding engagement with guide posts 51. Surrounding cylinder 31 and attached to the center thereof is a support 56 having a pair of vertically aligned pivot pins 57 extending into cylindrical bores in plates 53--54. To raise or lower cage 52 a threaded rod 58 is provided at" its lower end with a projecting flange 59 which is connected to plate 53 by a pair of bolts 60 (Fig. 3). Surrounding rod 58 and attached to the top of plate 47 is a hollow gear support 61 bored to receive and supvport abevel gear 62 which meshes with a bevel gear 63 driven by a reducing gear 64 which in turn is driven by a reversible electric motor 65. Reducing gear 64 and motor 65 are preferably mounted on plate 47, as shown. The motor illustrated is of the three phase induction type (see Fig. 2) in which the speed is controlled in a known manner by variable resistors R R .R connected to the secondary windings.

The extreme limits of oscillation of cylinder 31 about thrust bearings 57 are indicated at 66 and 67 in Fig. 2 in phantom lines.

Referring to Fig.4, oil or other fluid is supplied from a storage tank 68 to a pump 69 whose outlet is connected to conduit 70 through an adjustable valve 71 adapted to supply fluid at any desired pressure to con- .duit 70. Conduit 70 is also connected to storage tank .68 by an adjustable valve 72 and conduit 73, the valve 72 being constructed to open and pass fluid into conduit 73 if the pressure in conduit 70 due to the movement of piston 26 or 29 in its cylinder increases above the predetermined outlet pressure at which valve 71 is set. Valves 71 and 72 are preferably adjusted simul taneously by a common control or actuating member 74. Conduit 70 is connected through a multiple outlet valve 75 to a conduit 76 containing a valve 77 to fluid opening 37 into cylinder 31. A branch conduit 78 contain ing a valve 79 also connects conduit 76 to, opening 44 into piston 28. In the position of valve 75 shown in Fig. 4 it also connects fluid opening 34 at the end of conduit 80 with one end of a conduit 81 Whose other end terminates in storage tank 68. Valve 75 is rotated by a lever 82 and may be set to connect conduit 70 to conduit 80 to supply pressurized fluid to fluid opening 34 and simultaneously connect conduit 76 to conduit 81 to permit fluid in the rod end of cylinder 31 or piston rod 28 to return to storage tank 68. All the aforementioned conduits are made of rubber or other flexible material which will permit the movable parts of the machine to move freely.

In using the machine to form a workpiece capable of. being tensioned sufficiently by piston 26, bolts 39 are inserted in closure cap 35 to hold piston 29 near the head end of cylinder 31, as shown in Fig. 4. Die 14 is then secured to supports on table 11 and cage 52 is raised or lowered by operating motor 65 to bring the center line of piston rod into alignment with the center of die face 16. The operator moves control 74 to set valves 71 and 72 so that the pressure of the fluid against piston 26 when valve 79 is opened will cause the workpiece 17 to be stressed to or slightly beyond its elastic limit. With valve 77 closed, and valve 79 open, lever 82 is rotated to set valve 75 to connect conduit 70 to conduit 80 thereby supplying, fluid to the head end of piston 26 via bores 34 and 32 and causing the piston to advance chuck 23 toward die 14. Table 11 is also rotated by motor 13 in a clockwise direction (Fig. 2) to bring chuck 20 into position so that the ends of workpiece 17 may be gripped by the jaws of chucks 2i) and 23 when the workpiece is straight and not resting against the curved die face 16. Valve 75 is now set at the position shown in Fig. 4 to supply pressurized fluid to bore 44 and the rod end of piston 26 which causes chuck 23 to move away from chuck 20 and stretch workpiece 17 to or slightly beyond its elastic limit. Fluid at the rear end of piston 26 passes via bores 32, 34 and returns via conduits 80, 81 to storage tank 68. Although this fluid is applied to the rear end face of piston 29, this piston does not move since it is fluidlocked by reason of valve 77 being closed and additionally is mechanically locked against movement by bolts 39 (Fig. 2). Motor 13 (Fig. 2) is now started to rotate table 11 in the direction of the arrow which causes the workpiece to be wrapped against curved die face 16 and a portion of the workpiece to assume the shape of this face. As the forming proceeds, fluid from the rod end of tube 28 passes through opening 44 into conduit 78 and is returned to storage tank 68 via valve 72 which automatically opens to prevent the pressure of the fluid in tube 28 from increasing any further. It will be clear that if the pressure in tube 28 at the right of piston 26 increased substantially due to the motion of the piston, the tension on workpiece 17 might be increased by an amount sufficient to stretch it too much thereby making it too thin or even fracturing it. As the forming proceeds, the cylinder 31 oscillates about its pivotal supports 57 thereby permitting the straight unformed portion of workpiece 17 to remain tangent to curved die face 16 at each instant during the forming. When the forming is complete motor 13 is stopped and the formed workpiece removed from the chucks 20, 23 in an obvious manner.

Die 14 of Fig. 1 whose curved die face 16 lies in a horizontal plane may be replaced by the die 14 of Fig. 6 which has a curved peripheral face 16' which slopes upwardly from a low end 83 to a high end 84 in order to form an originally straight workpiece into one 17' which spirals upwardly, as shown. Before commencing the forming, motor 65 (Figs. 2 and 3) is operated to raise or lower cage 52 to bring the center line of piston rod 25 level with the middle of the low end 83 of die face 16'- The control resistance R R R of motor 65 is then adjusted so that when motor 65 is started, it rotates at the proper speed to continually raise cage 52 and chuck 23 at the same rate as the rise of inclined die face 16. The forming proceeds in the manner above described but with motor 65 running to continually raise the straight horizontal unformed portion of the workpiece to keep this portion tangent to the rising die face 16.

If a thicker, heavier workpiece 17a (Figs. 4 and 5) is to be bent to the contour of curved face 16a of die 14a attached to supports 15 on table 11, one end of the workpiece is gripped in the jaws of a heavy chuck 20a mounted on pivot pin 19. Chuck 23 is then screwed off the threaded end 24 of piston rod 25 and valve 75 set in the position shown in Fig. 4. With valve 77 closed and valve 79 open, valve 71 is now opened to supply fluid to opening 44 and the rod end of piston 26 thereby causing this piston to move toward piston 29 until the threaded end 24 of piston rod 25 is clear of the thread 41 as shown in Fig. 5, the fluid on the rear end of piston 26 passing via bores 32, 34 and conduits 80, 81 to tank 68. Valve 71 is now closed and a threaded closure plug 85 is screwed into thread 41, the length of plug 85 being such that it does not extend beyond thread 41. Plug 85 thus seals the opening at the rod end of piston rod 28. The bolts 39 are then removed from the machine and a heavy chuck 86 lowered down over closure cap 40. To permit this the chuck has apair of deep slots 87 in which the sides of cap 40 extend and the chuck has a pair of horizontal bores 88 to receive a pair of cylindrical securing pins 89 which pass through the same holes in cap 40 through which bolts 39 previously passed. The means described permits the chuck to be quickly and easily attached to cap 40 in a manner whereby the large tensile forces set up the chuck by workpiece 17a can be transmitted to cap 40 and piston rod 28. With one end of workpiece 17a fast in chuck 20a and with table 11 at rest, chuck 86 is advanced until its jaws (not shown) engage the end of workpiece 17a. This advancement is effected by closing valve 79, opening valve 77, rotating valve 75 until it connects conduit 70 to conduit 80 and then opening valve 71. Fluid is supplied by conduits 70 and 80 to opening 34 andthe head end of piston 29 causing the piston to advance toward the workpiece This fluid is also applied via bore 32 to the rear end face of piston 26 which does not move, however, since it is fluidlocked by reason of valve 79 being closed and additionally is mechanically locked against movement by reason of the plug 85 (Fig. 5) being in abutting engagement with the end of piston rod 25. To stretch workpiece 17a to or somewhat beyond its elastic limit, valve 75 is returned to the position shown in Fig. 4, valve 77 opened and valve 71 opened to supply pressure fluid to opening 37 and the rod end of piston 29. This pressure is sufiicient to move piston 29 and, chuck 86 by a distance suflicient to stretch the workpiece to or slightly beyond its elastic limit, fluid at the rear end of piston 29 passing via bore 34 and conduits 80, 81 to tank68. Motor 13 is started to rotate table 11 inthe directionshown by the arrow in Fig. 5, the rotation of the table causing the workpiece to be wrapped around the curved face 16a of die 14a and to be permanently bent to the desired shape. As piston 29 advances toward the rod end of cylinder 31 any substantial increase in fluid pressure in the cylinder above that established by the setting of valve 71 is prevented by the return of fluid to tank 68 through valve 72 and conduit 73. Motor 13 is now stopped and the ends of the formed workpiece removed from chucks 20a and 86.

In summary, it will be seen from the foregoing that there is provided a dual-piston workpiece tensioning means for a stretch forming machine in which the workpiece is connectable selectively at will to either of two concentric pistons to which fluid under pressure on the forward end thereof is selectively applied and released to initially stretch and subsequently resist forward movement of the workpiece toward the die while preventing movement of the other piston within its cylinder. This is accomplished by valves 71, 72, 77 and 79 of which either of valves 77, 79 is opened while the other is closed. Under this arrangement, fluid under pressure supplied via valve 71 and the opened one of valves 77, 79 moves the associated piston rearwardly within its cylinder to thereby initially tension the workpiece, and any pressure developed during subsequent forward movement of the piston in excess of that to which pressure release valve 72 is set is released via the opened valve and valve 72. The closed one of valves 77, 79 cuts off its associated piston from fluid pressure for moving the same rearwardly in its cylinder and also effects a fluid lock for preventing forward movement thereof within the cylinder. By reason of the fluid connection 32 between the concentric cylinders 28 and 31, means common to both pistons 26, 29 are employed for selectively applying or releasing fluid under pressure on the rear ends of both of the pistons in accordance with the setting of valve 75. In moving either piston forward within its cylinder in response to this fluid pressure on its rear end, its associated valve 77 or 79, as the case may be, is opened for fluid discharge and the tended to be embraced therein.

Having thus described my invention, what I claim as new and useful and desire to secure by Letters Patent is:

1. A combined bending and stretching machine for bending an elongated member to a predetermined shape comprising a base; a turntable rotatably supported thereon; a side face bending die connected to said turntable; means connecting the front end of said member to the turntable; means for rotating the turntable to wrap said member around the die while the rear end of the member is thereby drawn forward toward the die; a fluid pressure cylinder; a first. piston slidable in said cylinder;

a piston rod secured to said piston and having a long cylindrical bore; a closure cap secured to the front end of said piston rod and provided with a threaded outlet; a second piston slidable in said long bore; a second piston rod secured to said second piston and having its front end passing through said threaded outlet and exposed for detachably securing thereto of a chuck for gripping said rear end of said member; means common to both said pistons for selectively applying or releasing fluid under pressure on the head ends of said pistons; means for selectively applying and releasing fluid under'pressure on the rod end of either one of said pistons while preventing movement of the other of said pistons; means for supplying pressurized fluid to said long bore to advance said second piston toward the rear of said long bore and withdraw the front end of said second piston rod through and clear of said threaded outlet; a closure plug screwed into said threaded outlet; a chuck detachably secured to said closure cap and gripping the rear end of said member whereby said means for selectively applying fluid under pressure on the rod end of said first piston will resist forward movement thereof in the cylinder sufficiently to stretch said member substantially to its elastic limit; and means carried by said base for pivotally supporting said cylinder for movement about a vertical axis.

2. A combined stretching and bending machine for bending an elongated member to a predetermined shape comprising a susbtantially horizontal base; a turntable rotatably supported thereon for rotation about a vertical axis; a side face bending die carried by said turntable; means connecting the front end of said member to said turntable; a first piston rod; means detachably secured to the front end of said piston rod for gripping the rear end of said member; a first piston secured to the rear end of said piston rod; a hollow piston rod having an inner face along which said piston is slidable; an outwardly projecting cap extending across and secured to the front end of said hollow piston rod and provided with a central guide face along which said first piston rod is slidable; a second piston secured to the rear end of said hollow piston rod and having a small opening therethrough, said second piston having a diameter substantially greater than that of said first piston; a substantially horizontal hollow cylinder provided at its rear end with a closure having a small opening therethrough, the front end of said cylinder having an opening with whose marginal wall the outer face of said hollow piston rod has sliding contact; means on said base for pivotally supporting said cylinder for oscillation about a vertical axis remote from the axis of the turntable; means common to both said pistons and including said small openings for selectively applying or releasing fluid under pressure on. the head. ends of said pistons; means for applying and selectively releasing fluid under pressure on the rod end of either one: of said pistons while preventing movement of the other of. said pistons; means for introducing pressu-rized fluid into the: front end of said cylinder to move said second piston to the" rear end thereof; said cap having means for detachably securing. thereto of means for gripping said rear end of said member; removable securing. means: attached to the front end of said. cylinder and: to said cap to retain. said second piston near the rear end of said cylinder during the bending of the member against said die face whereby said means for selectively applying fluid under pressure to the rod end of said first pistonv will. resist forward movement of said. first piston snfliciently to. stretchv said member substantially to its elastie'limit.

3. A combined bending and stretching machine for bending an elongated member to a predetermined shape comprising a base; a turntable rotatably supported thereon; a side face bending die connected to said turntable; means connecting the front end of said member to the turntable; means for rotating the turntable to wrap said member around the die while. the rear end of the .member is thereby drawn: forward toward the die; a fluid pressure cylinder; means carried by said base for pivotally supporting said cylinder for movement about a vertical axis; a first piston slidable in said. cylinder; a piston rod secured to said piston andconnectable to said rear end of. said member, said piston. rod having a long cylindrical. bore terminating in a reduced opening at the forward end thereof; a second piston slidable in said long bore and having a piston rod extendable through said reduced opening and connectable to said rear end of said member; means common to both said pistons for selectivelyapplyingior. releasing fluid under pressure on the headends at said pistons; and means for selectively applying and; releasing: fluid under pressure on the. rod end. of. either ,oneof said? pistons to initially stretch said member and subsequently resist said forward movement thereof while preventing movement of the other of said pistons; V

References Cited inthe file of this patent UNITED STATES PATENTS 622,114 Burdett Mar. 28, 1899 644,294 Kennedy Feb. 27, 1900 1,035,828" Albree Aug. 20, I912 1,228,586 Mulvihill June 5, 1917 1,441,088 Hofstetter Jan. 2, 1923 1,964,003 McBr-ide n June 26, 1934 2,095,051 Bristol Oct. 5, 1937 2,103,984 Indge Dec. 28, 1937 2,105,198 McNamara Jan. 11, 1938 2,273,730 Varcoe et al'. Feb. 17, 1942 2,301,225 Muller Nov. 10, 1942 2,397,106 Haller Mar, 26, 1946 2,411,801 Nielson- Nov. 26, 1946 2,514,830 Bath July 11, 1950 2,536,738 Green Jan. 2, 1951 2,603,373 McFarland July 15, 1952 2,632,493 Gray' et a1. Mar. 24, 1953 2,638,860 Nobles May 19, 1953 2,708,344 Greer May 17, 1955 2,734,548 Fredericks Feb. 14', 1956 FOREIGN PATENTS 171,234 Great Britain Nov. 17, 1921 479,434 France Ian. 4, 1916 

